The invention relates to valves and valve seats, of the type used in general in hydraulic bodies for piston reciprocating pumps, being their main object the provision of an optimized valve and valve seat wherein a quadruple seal is provided assuring the closure tightness under all working conditions.
An important object of the instant invention is the arrangement which specially takes into account the assembling and disassembling operations for maintenance purposes, particularly in critical and severe installation requirements, as is the case in oil wells.
The main problem inherent to equipment employed in oil fields, including reciprocating pumps, is that originated by the valves used in the crude oil pumping circuit. The extremely severe operating conditions are strongly influenced by several factors such as temperature, pressures higher than those of the equipment, the aggression of the product per se and of materials such as sand, sludge, water and bacterial attack. These factors produce the quick wear of the valves included in the pumping hydraulic circuit and affect these valves such that they should be replaced after periods of time so short as 30 days.
This disadvantage is of concern since it affects production when the valve is not replaced at the proper time, further including the labor cost and that of spare parts. This situation is particularly notorious in those wells subject to recovery techniques, wherein water of the formation is sometimes injected, which increases the natural temperature of the product stored deep into the earth, which is commonly of higher viscosity. As a consequence the great amount of water, sludge and sand entrained quickly corrode the seats and valves of the equipment, thus turning it inoperative due to the high economic losses involved.
On the other hand, the relatively high temperatures involved result in dilatation of the pump body and of the valve seat support, which allows displacement of the seal away from its normal position, thus completely destroying its action.
Sometimes, the failure is produced at the tank level control, this resulting in overflow or emptying thereof. The filter blocking causes low suction and the corresponding negative hydraulic pressure, thus stopping the pumping action.
The above mentioned disadvantages result in the mandatory disassembly of the valve body to replace the valve and its seat. Frequently, the metal seat is nailed to the body, removal thereof being extremely difficult, requiring the use of large lever removers, heat dilatation of the body using a torch and removal of the seat, in some cases by oxy-cut. All these tasks increase cost and also the time involved in repairing the valve, thus decreasing safety.
The object of the invention is to facilitate maintenance operation and reduce the frequency between subsequent replacements, due to the fact that its special structure increases duration of the arrangement, specially in the cases of extremely severe operative conditions, as mentioned.
An additional object of the arrangement of the invention is its use as a spare part for any kind of pump employing seats and valves of the mentioned kind. Therefore, the shape and dimensions of the seat and of the valve per se are maintained, and the elements are manufactured in this case in three basic sizes to comply with the existing equipment. The only modification required could be the part of the body seat support which is adapted to the particular pump. Thus, the inventory of spare parts is reduced to a minimum and the only requirement is machining at the proper time the seat support required, thus giving a quick answer to a request for a determined part.
An alternative embodiment of the invention only affects the portion of the seat support which may be manufactured as an independent part or may be a part integrating the hydraulic body of the pump to which is applied, according to the features of the requested spare part. The same occurs with the nature of the seat of the sealing part which, apart from being frustoconical as is common at an angle of about 65xc2x0, it may also be planar at 90xc2x0 without varying the concept of the invention.
A very important factor to be considered of basic interest for the advantage afforded by the invention is that referred to maintenance tasks during which operators are in contact with the fluid being pumped. It is known that during the preparation and pumping steps of oil wells toxic chemical products are used, which obviously are damaging for the operators working with such products and metering them, in spite of the safety measures taken. As mentioned, the contact during reparation of each unit with such chemicals is unavoidable. Since the invention reduces considerably the need of several maintenance operations, the pollution risk also decreases, thus preserving the operators health.
Arrangements similar to that of the invention are already known. Examples thereof are the following:
U.S. Pat. No. 6,568 refers to xe2x80x9cImprovements in valves and seats thereforxe2x80x9d. This patent deals with a process for constructing check valves, discharge valves, and others. This invention relates to the combination of metal and non metal parts manufactured with refractory semi-plastic materials, such as those known at that time, such as ebonite, vulcanized rubber, etc.
U.S. Pat. No. 7,291, xe2x80x9cImprovements in the manufacturing of washing plugs and valves of general usexe2x80x9d. This invention was used in plugs, valves and seats of general use. It discloses practicing slots, recesses and cuts in order to locate a metal washer with which the contact and blocking region was defined for closing or regulated the passage of liquid, vapor or gas.
U.S. Pat. No. 7,773 relates to xe2x80x9cImprovements to valves and washing plugsxe2x80x9d, additional to the previous patent. In this patent, valve vanes have a longitudinal helical shape and provides the washing plugs with a part freely rotating within the plug, which carries a seal washer of the parent patent.
U.S. Pat. No. 32,203, xe2x80x9cCheck Valvexe2x80x9d. Among other members, it is comprised by an inner diaphragm having a central suction hole for housing the cone of a pump valve, forming a seat on which said check pump valve acts. Over the pump valve its housing has alignment and fastening guides for the retainer fitted into the slots by means of ears. The lower conical portion of the pump valve ends in a cylindrical shape as a guide for centering it into the suction and fastening hole above its seat. The pump valve includes a disk connecting the gasket and the retainer with years preventing the removal of the pump valve from its position.
U.S. Pat. No. 33,753, xe2x80x9cImproved Diaphragm Valvexe2x80x9d; U.S. Pat. No. 58,492, xe2x80x9cCheck Valve made of a Resilient Material Diskxe2x80x9d and U.S. Pat. No. 109,400 use blocking members made of resilient material which may not be used in the field of the product to be described.
U.S. Pat. No. 161,862 relates to a xe2x80x9cBall Valve seat ringxe2x80x9d, which being spherical, substantially differs from the object of the instant invention.
U.S. Pat. No. 198,828 refers to xe2x80x9cA seal closure to be used in the construction of a fluid valvexe2x80x9d. It is comprised by three members. The first member is movable with respect to the second member, which has a port communicating with he first member. The third member is located opposite to the second one. The closure includes a port seal portion adapted to be extended through the port, its inner edge being adapted for being in tight contact with the first member, and a body portion surrounding the port seal portion whose opposite sides are against the second and third member and in tight contact therewith and the fluid at the port urges the cited edge of the port seal portion towards a tight contact with the first member. This is a different structure which is not able to withstand high pressures due to its construction. It does not constitute an antecedent for the arrangement of the instant invention.
U.S. Pat. No. 209,373 refers to xe2x80x9cImprovements in the functional structure of disk valvesxe2x80x9d. It relates to a body divided into two equal modules. Each module is cylindrical, hollow, having a longer portion with a diameter smaller that that of a second integral portion of less height and larger diameter, comprising a flange with a peripheral wall integral to the base portion connecting to its similar part of the other module. The inner hollow portion of each module is a structural shape defining a first cylindrical space close to the end of the base portion wherein a closure means is housed.
U.S. Pat. No. 210,369, xe2x80x9cValve seal structurexe2x80x9d discloses a metal annular seal integral to a U-shaped inner sealing portion and a flexible band portion, which differs from the instant invention.
U.S. Pat. No. 252,849 relates to xe2x80x9cImprovements in valves for sludge pumps used in well drillingxe2x80x9d of the kind involved in the instant invention, since the valve is comprised by a mount having a conical seat on which a resilient periphery is adjusted typical of a resilient insert applied to a metal plate, including a mount bushing and a pin engaging with the closure means. The characterizing feature is that the metal plate is completely covered by a thermoplastic resilient wrapping including a margin portion provided by its frustoconical adjusting surface which covers its whole widths thus reproducing the conical adjusting surface at the mount seat. Subclaims mention that the plate is a planar disk-shaped part.
The essential feature, as shown in the drawings of the above cited patent, is that said frustoconical plate is wholly covered by a resilient material wrapping and seats, as in most of the known valves of the prior art, on the conical surface of the valve mount seat. Its novelty would be limited to the resilient material wrapping over the cited frustoconical plate.
Therefore, and comparing the specifications and drawings of the patents of the prior art to the object of the instant invention, no coincidences have been found and the problems solved by the instant invention are not overcome by the embodiments of the references of prior art cited.
In an attempt to overcome the mentioned disadvantages, seats made with thermoplastic materials such as poly amides have been made, as inserts into metal bodies or integrally made of such material. These seats were not successful due to the fact that the high pressures force the inserts out of the pump body, are easily deformed as a result of thermal effects, and no improvement is obtained in what concerns to tightness or to the duration of the sealing element.
As known, in oil fields known reciprocating pumping machines are used, which channel the fluid to collecting tanks, from which the oil is pumped to the treating plant. As mentioned above, pumps used during the initial process are those affected by the cited disadvantages, which implies a continuous intervention of corrective maintenance.
Most of the reciprocating pumps manufactured for the oil industry afford acceptable results and a reasonable duration of valve and their seats, provided the pumped fluid is oil free from polluting, corrosive or aggressive substances or elements.
However, in determined fields, conditions may be different due to the materials entrained in the fluid, particularly when carrying out secondary recovery, wherein production has been reduced and use is made of water injection. Since crude oil has a lower density it floats and ascends through the piping, carrying water percentages which sometimes are very high. At present, the recovery process is being carried out using hot water injection, which adds a thermal factor to worsen the conditions under which extraction is effected.
Moreover, this situation is even more critical when the oil pumped is highly viscous.
As mentioned, present pumping equipment uses piston reciprocating pumps in which the most damaged mechanical component is that comprised by the valves and their seats which become useless after a relatively short operating period, thus affecting output of the pumps due to losses produced through the damaged seal, which finally leads to the pump becoming out of service.
As soon as this problem is detected, it should be immediately solved since, as fluid from the well continues flowing, the collecting tank may overflow due to lack of pumping activity.
An additional reason intervening in the destruction of the valve seat, apart from other corrosive agents, is the bacterial action. Particularly, a solution to this problem is afforded by using bactericide chemical products, which requires the use of safe means for operators in charge of metering such chemicals and of maintenance tasks due to the high toxicity via skin or mucous membranes.
Summarizing, during operation of reciprocating pumps the main problems originated are essentially due to several causes such as abrasion, corrosion and thermal effects, and most important, the bacterial attack.
The solution to all the mentioned problems originated day by day in mixture pumping plants as those mentioned, is attained with the arrangement of the invention which produced an important increase in the duration of valve seats, event under the mentioned severe operating conditions. In the private tests, a considerable increase in the continuous operation has been obtained, without maintenance of any kind. Further, upon detection of wear at the valve seat, repairing operations may be carried out easily and the part may be replaced several times at a low cost, assembly not representing a complex task as was till now.
The valve threaded seat support with quadruple seal of the invention is comprised by a preferably metal body inside which a thread has been practiced, covering the central region comprised between a cylindrical upper mouth having a larger diameter and a lower cylindrical region having a smaller diameter defining a step adjacent the thread fillet, while the valve body has a frustoconical seat at 65xc2x0 or more, up to 90xc2x0, i.e. with a planar seat at the upper portion.
The larger diameter seat forms a peripheral upper edge followed by a cylindrical strip of smaller diameter with a peripheral channel wherein an O-ring is adapted, after which a smaller diameter region is located carrying the thread fillets. At the interior there is a central drill for a rod guiding the valve blocking disk, surrounded by fluid passage ducts. The body of the threaded seat, at least partially, of the blocking disk and of the guide rod are made of a crystalline homopolymer acetalic resin (xe2x80x9cDelrinxe2x80x9d) or of a long chain synthetic polymeric amide with periodical amide groups at the main chain, the generic name of which is xe2x80x9cNylonxe2x80x9d.
A preferred embodiment of the threaded seat support for valve with quadruple seal of the invention will be now described with reference to the accompanying drawings, which are not to be considered as limiting the scope of the invention, but merely with illustrative purposes.